Plasma processing method and apparatus

ABSTRACT

A plasma processing method for generating plasma in a vacuum chamber and processing a substrate placed on a substrate electrode, the plasma being generated by supplying a high-frequency power having a frequency of 50 MHz to 3 GHz to an antenna provided opposite to the substrate electrode while interior of the vacuum chamber is controlled to a specified pressure by supplying a gas into the vacuum chamber and exhausting the interior of the vacuum chamber, the method includes with a dielectric plate being sandwiched between the antenna and the vacuum chamber and both the antenna and the dielectric plate projecting into the vacuum chamber, controlling plasma distribution on the substrate with an annular and recessed slit provided between the antenna and the vacuum chamber, and processing the substrate in a state where the antenna cover is fixed by making both an inner side face of the slit and the antenna covered with an antenna cover, making a bottom face of the slit covered with a slit cover, supporting the antenna cover by the slit cover, and fixing the slit cover to a wall surface of the vacuum chamber.

[0001] This is a continuation-in-part of Ser. No. 09/968,810, filed Oct.3, 2001.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a plasma processing method andapparatus to be used for manufacture of semiconductor or other electrondevices and micromachines.

[0003] In the manufacture of semiconductor or other electron devices andmicromachines, thin-film processing techniques using plasma processinghave been becoming increasingly important in recent years.

[0004] As an example of conventional plasma processing methods, plasmaprocessing using a patch-antenna type plasma source is described belowwith reference to FIG. 5. Referring to FIG. 5, while interior of avacuum chamber 1 is maintained to a specified pressure by introducing aspecified gas from a gas supply unit 2 into the vacuum chamber 1 andsimultaneously performing exhaustion by a turbo-molecular pump 3 as anexhauster, a high-frequency power of 100 MHz is supplied by an antennause high-frequency power supply 4 to an antenna 5 provided so as toproject into the vacuum chamber 1. Then, plasma is generated in thevacuum chamber 1, allowing plasma processing to be carried out with asubstrate 7 placed on a substrate electrode 6. There is also provided asubstrate-electrode use high-frequency power supply 8 for supplyinghigh-frequency power to the substrate electrode 6, making it possible tocontrol ion energy that reaches the substrate 7. The high-frequencyvoltage supplied to the antenna 5 is delivered to a proximity to thecenter of the antenna 5 by a feed bar 9. A plurality of sites of theantenna 5 other than its center and peripheries, and a face 27 of thevacuum chamber 1 opposite to the substrate 7 are short-circuited byshort pins 10. A dielectric plate 11 is sandwiched between the antenna 5and the vacuum chamber 1, and the feed bar 9 and the short pins 10 serveto connect the antenna 5 and the antenna use high-frequency power supply4 to each other, and the antenna 5 and the vacuum chamber 1 to eachother via through holes provided in the dielectric plate 11. Also,surfaces of the antenna 5 are covered with an antenna cover 15. Theantenna cover 15 is fixed to the antenna 5 by bolts 25. Further, a slit14 is provided so as to comprise a recessed or grooved space between thedielectric plate 11 and a dielectric ring 12 provided at a peripheralportion of the dielectric plate 11, and a recessed or grooved spacebetween the antenna 5 and a conductor ring 13 provided at a peripheralportion of the antenna 5.

[0005] The turbo-molecular pump 3 and an exhaust port 19 are disposedjust under the substrate electrode 6, and a pressure-regulating valve 20for controlling the vacuum chamber 1 to a specified pressure is anup-and-down valve disposed just under the substrate electrode 6 and justover the turbo-molecular pump 3. The substrate electrode 6 is fixed tothe vacuum chamber 1 with four pillars 21.

[0006] In the plasma processing described in the above prior-artexample, however, plasma density would become the highest at the slit,posing an issue of damage of a bottom face 26 of the slit. The vacuumchamber, which is typically made of aluminium, is generally coated withanodic oxide (alumite) for prevention of corrosion of the inner wallsurface of the vacuum chamber. However, the alumite of the slit bottomface would be damaged and, over repeated plasma processing, the alumitewould become gradually thinner and thinner. According to ourexperiments, when the thickness of alumite was measured before and afteran about 1,000 pcs. etching process, an about 10 μm decrease of filmthickness was found. Shortage of the alumite thickness would lead toproblems such as corrosion of base-material aluminium or occurrence ofdust. For prevention of this, it is necessary to disassemble most of theplasma source unit and replace the aluminium member, which is heavy andexpensive, unfortunately. Furthermore, since the antenna cover 15 isfixed to the antenna 5 by the bolts 25, deposited film resulting fromthe plasma processing tends to be peeled off from the vicinities of thebolts 25, causing occurrence of dust, as another problem.

[0007] Meanwhile, in the plasma processing described in the prior-artexample, there is an issue that the temperature of the antenna cover 15increases due to plasma exposure. Since the antenna cover 15 and theantenna 5 are vacuum-insulated from each other, the temperature of theantenna cover 15 gradually increases over repeated plasma processing.According to our experiments, it was found that the temperature of theantenna cover 15 increases up to 170° C. after 5-min. plasma processingand 1-min. vacuum holding is repeated six times. Such an abrupt changein the temperature of the antenna cover 15 may cause not only occurrenceof dust but also cracks of the antenna cover 15.

[0008] In view of these and other prior-art issues, an object of thepresent invention is to provide a plasma processing method and apparatuswhich is less liable to occurrence of dust and cracks of the antennacover.

SUMMARY OF THE INVENTION

[0009] In accomplishing these and other aspects, according to a firstaspect of the present invention, there is provided a plasma processingmethod for generating plasma in a vacuum chamber and processing asubstrate placed on a substrate electrode, the plasma being generated bysupplying a high-frequency power having a frequency of 50 MHz to 3 GHzto an antenna provided opposite to the substrate electrode whileinterior of the vacuum chamber is controlled to a specified pressure bysupplying a gas into the vacuum chamber and exhausting the interior ofthe vacuum chamber,

[0010] the method comprising: with a dielectric plate being sandwichedbetween the antenna and the vacuum chamber and both the antenna and thedielectric plate projecting into the vacuum chamber,

[0011] controlling plasma distribution on the substrate with an annularand recessed slit provided between the antenna and the vacuum chamber;and

[0012] processing the substrate in a state where the antenna cover isfixed by making both an inner side face of the slit and the antennacovered with an antenna cover, making a bottom face of the slit coveredwith a slit cover, supporting the antenna cover by the slit cover, andfixing the slit cover to a wall surface of the vacuum chamber.

[0013] According to a second aspect of the present invention, there isprovided a plasma processing method according to the first aspect,wherein the substrate is processed with the slit cover is a conductorand with electric conduction between the slit cover and thevacuum-chamber wall surface ensured by a spiral tube.

[0014] According to a third aspect of the present invention, there isprovided a plasma processing method according to the first aspect,wherein the substrate is processed with the slit cover is an insulatingmember.

[0015] According to a fourth aspect of the present invention, there isprovided a plasma processing method for generating plasma in a vacuumchamber and processing a substrate placed on a substrate electrodewithin the vacuum chamber, the plasma being generated by supplying ahigh-frequency power having a frequency of 50 MHz to 3 GHz to an antennaprovided opposite to the substrate electrode while interior of thevacuum chamber is controlled to a specified pressure by supplying a gasinto the vacuum chamber and exhausting the interior of the vacuumchamber,

[0016] the method comprising: with a dielectric plate being sandwichedbetween the antenna and the vacuum chamber and both the antenna and thedielectric plate projecting into the vacuum chamber,

[0017] controlling plasma distribution on the substrate by an annularand recessed slit provided between the antenna and the vacuum chamber;and

[0018] processing the substrate while controlling temperature of theantenna by making both an inner side face of the slit and the antennacovered with an antenna cover and applying a refrigerant flow to theantenna while ensuring heat conduction between the antenna and theantenna cover by a heat-conducting sheet provided between the antennaand the antenna cover.

[0019] According to a fifth aspect of the present invention, there isprovided a plasma processing method according to the fourth aspect,wherein the substrate is processed while the temperature of the antennais controlled with the heat-conducting sheet being made from a resinhaving elasticity and having a dielectric loss tangent of more than 0and not more than 0.01.

[0020] According to a sixth aspect of the present invention, there isprovided a plasma processing method according to the fourth aspect,wherein the substrate is processed while the temperature of the antennais controlled with the heat-conducting sheet having a thickness of 0.03mm to 3 mm.

[0021] According to a seventh aspect of the present invention, there isprovided a plasma processing method according to the first aspect,wherein the antenna cover is made of 1 mm to 10 mm thick quartz glass.

[0022] According to an eighth aspect of the present invention, there isprovided a plasma processing method according to the first aspect,wherein the substrate is processed with the antenna cover being made of1 mm to 10 mm thick insulative silicon.

[0023] According to a ninth aspect of the present invention, there isprovided a plasma processing method according to the first aspect,wherein the substrate is processed with the frequency of thehigh-frequency power supplied to the antenna being within a range of 50MHz to 300 MHz.

[0024] According to a 10th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0025] a vacuum chamber;

[0026] a gas supply unit for supplying gas into the vacuum chamber;

[0027] an exhausting unit for exhausting interior of the vacuum chamber;

[0028] a pressure-regulating valve for controlling the interior of thevacuum chamber to a specified pressure;

[0029] a substrate electrode for placing thereon a substrate within thevacuum chamber;

[0030] an antenna provided opposite to the substrate electrode; and

[0031] high-frequency power supply capable of supplying a high-frequencypower having a frequency of 50 MHz to 3 GHz to the antenna,

[0032] the plasma processing apparatus further comprising:

[0033] a dielectric plate sandwiched between the antenna and the vacuumchamber, both the antenna and the dielectric plate projecting into thevacuum chamber;

[0034] an antenna cover for covering both an inner side face of anannular and recessed slit and the antenna with the slit provided betweenthe antenna and the vacuum chamber; and

[0035] a slit cover for covering a bottom face of the slit andsupporting the antenna cover, where the slit cover is fixed to a wallsurface of the vacuum chamber so that the antenna cover is fixed.

[0036] According to an 11th aspect of the present invention, there isprovided a plasma processing apparatus according to the 10th aspect,wherein the slit cover is a conductor and electric conduction betweenthe slit cover and the vacuum-chamber wall surface is ensured by aspiral tube.

[0037] According to a 12th aspect of the present invention, there isprovided a plasma processing apparatus according to the 10th aspect,wherein the slit cover is a dielectric substance.

[0038] According to a 13th aspect of the present invention, there isprovided a plasma processing apparatus comprising:

[0039] a vacuum chamber;

[0040] a gas supply unit for supplying gas into the vacuum chamber;

[0041] an exhausting unit for exhausting interior of the vacuum chamber;

[0042] a pressure-regulating valve for controlling the interior of thevacuum chamber to a specified pressure;

[0043] a substrate electrode for placing thereon a substrate within thevacuum chamber;

[0044] an antenna provided opposite to the substrate electrode; and

[0045] high-frequency power supply capable of supplying a high-frequencypower having a frequency of 50 MHz to 3 GHz to the antenna,

[0046] the plasma processing apparatus further comprising:

[0047] a dielectric plate sandwiched between the antenna and the vacuumchamber, both the antenna and the dielectric plate projecting into thevacuum chamber;

[0048] an antenna cover for covering both an inner side face of anannular and recessed slit and the antenna with the slit provided betweenthe antenna and the vacuum chamber;

[0049] a heat-conducting sheet provided between the antenna and theantenna cover; and

[0050] a refrigerant feed unit for making a refrigerant flow to theantenna.

[0051] According to a 14th aspect of the present invention, there isprovided a plasma processing apparatus according to the 13th aspect,wherein the heat-conducting sheet is made from a resin having elasticityand having a dielectric loss tangent of more than 0 and not more than0.01.

[0052] According to a 15th aspect of the present invention, there isprovided a plasma processing apparatus according to the 13th aspect,wherein the heat-conducting sheet has a thickness of 0.03 mm to 3 mm.

[0053] According to a 16th aspect of the present invention, there isprovided a plasma processing apparatus according to the tenth aspect,wherein the antenna cover is made of 1 mm to 10 mm thick quartz glass.

[0054] According to a 17th aspect of the present invention, there isprovided a plasma processing apparatus according to the tenth aspect,wherein the antenna cover is made of 1 mm to 10 mm thick insulativesilicon.

[0055] According to an 18th aspect of the present invention, there isprovided a plasma processing apparatus according to the tenth aspect,wherein the frequency of the high-frequency power supplied to theantenna is within a range of 50 MHz to 300 MHz.

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] These and other aspects and features of the present inventionwill become clear from the following description taken in conjunctionwith the preferred embodiments thereof with reference to theaccompanying drawings, in which:

[0057]FIG. 1 is a sectional view showing constitution of a plasmaprocessing apparatus used in a first embodiment of the presentinvention;

[0058]FIG. 2 is a sectional view showing a part of the constitution ofthe plasma processing apparatus used in the first embodiment of thepresent invention;

[0059]FIG. 3 is a sectional view showing constitution of a plasmaprocessing apparatus used in a second embodiment of the presentinvention;

[0060]FIG. 4 is a sectional view showing constitution of a plasmaprocessing apparatus used in a third embodiment of the presentinvention; and

[0061]FIG. 5 is a sectional view showing constitution of a plasmaprocessing apparatus used in a prior-art example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] Before the description of the present invention proceeds, it isto be noted that like parts are designated by like reference numeralsthroughout the accompanying drawings.

[0063] Hereinbelow, a first embodiment of the present invention isdescribed with reference to FIGS. 1 and 2.

[0064]FIG. 1 shows a sectional view of a plasma processing apparatus,used in the first embodiment of the present invention, on which apatch-antenna system plasma source is mounted. Referring to FIG. 1,while interior of a vacuum chamber 1 is maintained to a specifiedpressure by introducing a specified gas from a gas supply unit 2 intothe vacuum chamber 1 and simultaneously performing exhaustion by aturbo-molecular pump 3 as an exhauster, a high-frequency power of 100MHz is supplied by an antenna use high-frequency power supply 4 to anantenna 5 provided so as to project into the vacuum chamber 1. Then,plasma is generated in the vacuum chamber 1, allowing plasma processingto be carried out with a substrate 7 placed on a substrate electrode 6.There is also provided a substrate-electrode use high-frequency powersupply 8 for supplying a high-frequency power of 400 kHz to thesubstrate electrode 6, making it possible to control ion energy thatreaches the substrate 7. The high-frequency power supplied to theantenna 5 is delivered to a proximity to the center of the antenna 5 bya feed bar 9. A plurality of sites of the antenna 5 other than itscenter and peripheries, and a face 27 of the vacuum chamber 1 oppositeto the substrate 7 are short-circuited by short pins 10. A dielectricplate 11 is sandwiched between the antenna 5 and the vacuum chamber 1,and the feed bar 9 and the short pins 10 extend through through holesprovided in the dielectric plate 11. Further, a slit 14 is provided soas to comprise a recessed or grooved space between the dielectric plate11 and a dielectric ring 12 provided at a peripheral portion of thedielectric plate 11, and a recessed or grooved space between the antenna5 and a conductor ring 13 provided at a peripheral portion of theantenna 5.

[0065] An inner side face of the slit 14 and the antenna 5 are coveredwith, for example, a 5 mm thick antenna cover 15 made of quartz glass, abottom face of the slit 14 is covered with a slit cover 16, and theantenna cover 15 is supported by the slit cover 16, where the slit cover16 is fixed to a vacuum-chamber wall surface 17 so that the antennacover 15 is fixed. Also, the slit cover 16 is given by an about 5 mmthick conductor (aluminium coated with alumite), and conduction betweenthe slit cover 16 and the vacuum-chamber wall surface 17 is ensured by aradially elastic and conductive spiral tube 18 made of metal etc.

[0066] The turbo-molecular pump 3 and an exhaust port 19 are disposedjust under the substrate electrode 6, and a pressure-regulating valve 20for controlling the vacuum chamber 1 to a specified pressure is anup-and-down valve disposed just under the substrate electrode 6 and justover the turbo-molecular pump 3. The substrate electrode 6 is fixed tothe vacuum chamber 1 with four pillars 21.

[0067]FIG. 2 shows a plan view of the antenna 5. In FIG. 2, the shortpins 10 are provided at three sites so as to be equidistantly placed tothe center of the antenna 5.

[0068] With the plasma processing apparatus described above, when thethickness of alumite of the slit cover was measured before and after anabout 1,000 pcs. etching process, an about 10 μm decrease of filmthickness was found. However, by virtue of the slit cover's light weightand low price, plasma processing was able to be continued with the slitcover replaced as a consumption part.

[0069] Also, since there are no such singular points as bolt fittingholes at the surface of the antenna cover 15, deposited film resultingfrom the plasma processing was free from peeling, with the result ofalmost no dust occurrence.

[0070] Next, a second embodiment of the present invention is describedwith reference to FIG. 3.

[0071]FIG. 3 shows a sectional view of a plasma processing apparatus,used in the second embodiment of the present invention, on which apatch-antenna system plasma source is mounted. Referring to FIG. 3,while interior of a vacuum chamber 1 is maintained to a specifiedpressure by introducing a specified gas from a gas supply unit 2 intothe vacuum chamber 1 and simultaneously performing exhaustion by aturbo-molecular pump 3 as an exhauster, a high-frequency power of 100MHz is supplied by an antenna use high-frequency power supply 4 to anantenna 5. Then, plasma is generated in the vacuum chamber 1, allowingplasma processing to be carried out with a substrate 7 placed on asubstrate electrode 6. There is also provided a substrate-electrode usehigh-frequency power supply 8 for supplying a high-frequency power of400 kHz to the substrate electrode 6, making it possible to control ionenergy that reaches the substrate 7. The high-frequency power suppliedto the antenna 5 is delivered to a proximity to the center of theantenna 5 by a feed bar 9. A plurality of sites of the antenna 5 otherthan its center and peripheries, and a face 27 of the vacuum chamber 1opposite to the substrate 7 are short-circuited by short pins 10. Adielectric plate 11 is sandwiched between the antenna 5 and the vacuumchamber 1, and the feed bar 9 and the short pins 10 extend throughthrough holes provided in the dielectric plate 11. Further, a slit 14 isprovided so as to comprise a recessed or grooved space between thedielectric plate 11 and a dielectric ring 12 provided at a peripheralportion of the dielectric plate 11, and a recessed or grooved spacebetween the antenna 5 and a conductor ring 13 provided at a peripheralportion of the antenna 5.

[0072] An inner side face of the slit 14 and the antenna 5 are coveredwith, for example, a 5 mm thick antenna cover 15 made of quartz glass. A0.2 mm thick heat-conducting sheet 22 made of silicon resin (dielectricloss tangent=0.005) and having such an elasticity as to allow thetolerance is provided between the antenna 5 and the antenna cover 15 asone example, and a refrigerant feed unit 23 such as a pump for making arefrigerant flow to the antenna 5 is provided. In addition, arefrigerant flow passage 24 is formed inside the antenna 5, and inletand outlet passages for the refrigerant are provided inside the feed bar9.

[0073] The turbo-molecular pump 3 and an exhaust port 19 are disposedjust under the substrate electrode 6, and a pressure-regulating valve 20for controlling the vacuum chamber 1 to a specified pressure is anup-and-down valve disposed just under the substrate electrode 6 and justover the turbo-molecular pump 3. The substrate electrode 6 is fixed tothe vacuum chamber 1 with four pillars 21. Planar arrangement of theshort pins 10 is the same as in FIG. 2, which has already beendescribed.

[0074] With the plasma processing apparatus of the above-describedconstitution, even after 5-min. plasma processing and 1-min. vacuumholding was repeated 100 times, the temperature of the antenna cover 15was maintained under 100° C. The reason of this can be considered thatthe thin heat-conducting sheet 22 was interleaved between the antennacover 15 and the antenna 5 and that the antenna 5 was cooled by arefrigerant. The silicon resin heat-conducting sheet 22 is soft, makingclose contact with the antenna 5 and the antenna cover 15, and thin,having a great effect in accelerating heat exchange between the antennacover 15 and the antenna 5. As a result of carrying out plasmaprocessing while the temperature of the antenna cover 15 was controlledas shown above, there was neither occurrence of dust nor occurrence ofcracks of the antenna cover 15.

[0075] Next, a third embodiment of the present invention is describedwith reference to FIG. 4.

[0076]FIG. 4 shows a sectional view of a plasma processing apparatus,used in the third embodiment of the present invention, on which apatch-antenna system plasma source is mounted. Referring to FIG. 4,while interior of a vacuum chamber 1 is maintained to a specifiedpressure by introducing a specified gas from a gas supply unit 2 intothe vacuum chamber 1 and simultaneously performing exhaustion by aturbo-molecular pump 3 as an exhauster, a high-frequency power of 100MHz is supplied by an antenna use high-frequency power supply 4 to anantenna 5. Then, plasma is generated in the vacuum chamber 1, allowingplasma processing to be carried out with a substrate 7 placed on asubstrate electrode 6. There is also provided a substrate-electrode usehigh-frequency power supply 8 for supplying a high-frequency power of400 kHz to the substrate electrode 6, making it possible to control ionenergy that reaches the substrate 7. The high-frequency power suppliedto the antenna 5 is delivered to a proximity to the center of theantenna 5 by a feed bar 9. A plurality of sites of the antenna 5 otherthan its center and peripheries, and a face 27 of the vacuum chamber 1opposite to the substrate 7 are short-circuited by short pins 10. Adielectric plate 11 is sandwiched between the antenna 5 and the vacuumchamber 1, and the feed bar 9 and the short pins 10 extend throughthrough holes provided in the dielectric plate 11. Further, a slit 14 isprovided so as to comprise a recessed or grooved space between thedielectric plate 11 and a dielectric ring 12 provided at a peripheralportion of the dielectric plate 11, and a recessed or grooved spacebetween the antenna 5 and a conductor ring 13 provided at a peripheralportion of the antenna 5.

[0077] An inner side face of the slit 14 and the antenna 5 are coveredwith, for example, a 5 mm thick antenna cover 15 made of quartz glass, abottom face of the slit 14 is covered with a slit cover 16, and theantenna cover 15 is supported by the slit cover 16, where the slit cover16 is fixed to a vacuum-chamber wall surface 17 so that the antennacover 15 is fixed. Also, the slit cover 16 is given by a conductor(aluminium coated with alumite), and electric conduction between theslit cover 16 and the vacuum-chamber wall surface 17 is ensured by aradially elastic and conductive spiral tube 18 made of metal etc.

[0078] A 0.2 mm thick heat-conducting sheet 22 made of silicon resin(dielectric loss tangent=0.005) is provided between the antenna 5 andthe antenna cover 15 as one example, and a refrigerant feed unit 23 formaking a refrigerant flow to the antenna 5 is provided. In addition, arefrigerant flow passage 24 is formed inside the antenna 5, and inletand outlet passages for the refrigerant are provided inside the feed bar9.

[0079] The turbo-molecular pump 3 and an exhaust port 19 are disposedjust under the substrate electrode 6, and a pressure-regulating valve 20for controlling the vacuum chamber 1 to a specified pressure is anup-and-down valve disposed just under the substrate electrode 6 and justover the turbo-molecular pump 3. The substrate electrode 6 is fixed tothe vacuum chamber 1 with four pillars 21. Planar arrangement of theshort pins 10 is the same as in FIG. 2, which has already beendescribed.

[0080] With the plasma processing apparatus of the above-describedconstitution, when the thickness of alumite of the slit cover wasmeasured before and after an about 1,000 pcs. etching process, an about10 μm decrease of film thickness was found. However, by virtue of theslit cover's light weight and low price, plasma processing was able tobe continued with the slit cover replaced as a consumption part.

[0081] Also, since there are no such singular points as bolt fittingholes at the surface of the antenna cover 15, deposited film resultingfrom the plasma processing was free from peeling, with the result ofalmost no dust occurrence.

[0082] Further, even after 5-min. plasma processing and 1-min. vacuumholding was repeated 100 times, the temperature of the antenna cover 15was maintained under 100° C. The reason of this can be considered thatthe thin heat-conducting sheet 22 was interleaved between the antennacover 15 and the antenna 5 and that the antenna 5 was cooled by arefrigerant. The silicon resin heat-conducting sheet 22 is soft, makingtight contact with the antenna 5 and the antenna cover 15, and thin,having a great effect in accelerating heat exchange between the antennacover 15 and the antenna 5. As a result of carrying out plasmaprocessing while the temperature of the antenna cover 15 was controlledas shown above, there was neither occurrence of dust nor occurrence ofcracks of the antenna cover 15.

[0083] The above embodiments of the present invention have exemplifiedonly part of many variations on configuration of the vacuum chamber,structure and arrangement of the plasma source, and the like out of theapplication range of the present invention. Needless to say, other manyvariations may be conceived in applying the present invention, otherthan the examples given above.

[0084] The above embodiments of the present invention have beendescribed on a case where the slit cover is a conductor and theconduction between the slit cover and the vacuum-chamber wall surface isensured by the spiral tube. Ensuring the conduction between the slitcover and the vacuum-chamber wall surface produces advantages that anelectromagnetic field excited inside the vacuum chamber is stabilizedwhile occurrence of abnormal discharges can be suppressed. Otherwise,even if the slit cover is an insulating member, similar advantages canbe obtained.

[0085] Also, the above embodiments of the present invention have beendescribed on a case where the heat-conducting sheet is 0.2 mm thicksilicon resin and has a dielectric loss tangent of 0.005. However, thethickness and material of the heat-conducting sheet are not limited tothese. Although the heat-conducting sheet is desirably soft so as to besuperior in close contactability in order to enhance the heat exchangebetween the antenna and the antenna cover, excessively thin sheets lessthan 0.03 mm could not absorb insufficiency of the flatness of theantenna or the antenna cover, and excessively thick sheets more than 3mm would cause increases in the heat capacity of the heat-conductingsheet itself. Thus, preferably, the thickness of the heat-conductingsheet is generally in a range of 0.03 mm to 3 mm. Further, largerdielectric loss tangents of the heat-conducting sheet might causeoccurrence of dielectric loss due to an effect of the high-frequencypower supplied to the antenna, giving rise to heat generation andmelting of the resin. Therefore, preferably, the dielectric loss tangentis generally more than 0 and not more than 0.01. Also, although theabove embodiments have been described on a case where the antenna coveris 5 mm quartz glass, yet it would be possible that the antenna cover ismade from other ceramic base materials or insulative silicon. However,ceramic base materials contain not small quantities of impurities, andtherefore may cause dust or contamination, thus not so preferable. Usinginsulative silicon, on the other hand, has an effect of improving theetching selection ratio in the etching process of silicon oxide or otherinsulating films. Still also, excessively thin antenna covers less than1 mm would cause insufficiency of mechanical strength, while excessivelythick antenna covers more than 10 mm would cause decreases in coolingefficiency due to a heat storage effect. Thus, preferably, the thicknessof the antenna cover is generally in a range of 1 mm to 10 mm.

[0086] Also, the above embodiments have been described on a case where ahigh-frequency voltage is delivered to the antenna via a through holeprovided at a proximity to the center of the dielectric plate and wherethe antenna and the vacuum chamber are short-circuited by short pins viathrough holes provided at a plurality of sites other than the center andperipheries of the dielectric plate and which are equidistantly placedto the center of the antenna. With such an arrangement, isotropy of theplasma can be enhanced. With small substrates or the like, it isneedless to say that sufficiently high in-plane uniformity can beobtained without using short pins.

[0087] Also, the above embodiments have been described on a case wherethe frequency of the high-frequency power applied to the antenna is 100MHz. However, frequencies of 50 MHz to 3 GHz can be used for the patchantenna used in the present invention.

[0088] However, the present invention is notably effective for caseswhere the frequency of the high-frequency power applied to the antenna,in particular, is within a range of 50 MHz to 300 MHz.

[0089] Use of frequencies lower than 50 MHz would make it hard to form ahigh-density plasma region based on hollow cathode discharge by theslit, where the control of plasma density using the slit could notsufficiently be implemented.

[0090] With the frequency higher than 300 MHz, conversely, plasmaignition would be hard to turn on.

[0091] Also, the above embodiments have been described on a case wherethe frequency of the high-frequency power supplied to the substrateelectrode is 400 kHz. However, needless to say, high-frequency power ofother frequencies, e.g. 100 kHz to 100 MHz, can be used for the controlof ion energy that reaches the substrate. Otherwise, without the supplyof high-frequency power to the substrate electrode, it is also possibleto carry out plasma processing with weak ion energy by making use of aslight difference between plasma potential and substrate potential.

[0092] Galden can be used as an example of the refrigerant. Galden is afluorine-based solution called perfluoropolyether. Galden is a verycommon refrigerant, and it seems needless to mention any examples of itsmanufacturers (ex. Ausimont company, Italy). Galden is low in vaporpressure and poor at volatility, requiring no frequent resupply. Galdenis low in chemical reactivity, allowing safe handling.

[0093] It is also possible to use water as the refrigerant. Inparticular, DIW (De-Ionized Water) is widely used. Using DIW produces aneffect of less deposition of contaminations inside the piping (comparedwith tap water).

[0094] As apparent from the above description, according to the firstaspect of the present invention, there is provided a plasma processingmethod for generating plasma in a vacuum chamber and processing asubstrate placed on a substrate electrode, the plasma being generated bysupplying a high-frequency power having a frequency of 50 MHz to 3 GHzto an antenna provided opposite to the substrate electrode whileinterior of the vacuum chamber is controlled to a specified pressure bysupplying a gas into the vacuum chamber and exhausting the interior ofthe vacuum chamber,

[0095] the method comprising: with a dielectric plate being sandwichedbetween the antenna and the vacuum chamber and both the antenna and thedielectric plate projecting into the vacuum chamber,

[0096] controlling plasma distribution on the substrate with an annularand recessed slit provided between the antenna and the vacuum chamber;and

[0097] processing the substrate in a state where the antenna cover isfixed by making both an inner side face of the slit and the antennacovered with an antenna cover, making a bottom face of the slit coveredwith a slit cover, supporting the antenna cover by the slit cover, andfixing the slit cover to a wall surface of the vacuum chamber.Therefore, a plasma processing method which is less liable to occurrenceof dust can be provided.

[0098] Also, according to the second aspect of the present invention,there is provided a plasma processing method for generating plasma in avacuum chamber and processing a substrate placed on a substrateelectrode within the vacuum chamber, the plasma being generated bysupplying a high-frequency power having a frequency of 50 MHz to 3 GHzto an antenna provided opposite to the substrate electrode whileinterior of the vacuum chamber is controlled to a specified pressure bysupplying a gas into the vacuum chamber and exhausting the interior ofthe vacuum chamber,

[0099] the method comprising: with a dielectric plate being sandwichedbetween the antenna and the vacuum chamber and both the antenna and thedielectric plate projecting into the vacuum chamber,

[0100] controlling plasma distribution on the substrate by an annularand recessed slit provided between the antenna and the vacuum chamber;and

[0101] processing the substrate while controlling temperature of theantenna by making both an inner side face of the slit and the antennacovered with an antenna cover and applying a refrigerant flow to theantenna while ensuring heat conduction between the antenna and theantenna cover by a heat-conducting sheet provided between the antennaand the antenna cover. Therefore, a plasma processing method which isless liable to occurrence of dust and cracks of the antenna cover can beprovided.

[0102] Also, according to the third aspect of the present invention,there is provided a plasma processing apparatus comprising:

[0103] a vacuum chamber;

[0104] a gas supply unit for supplying gas into the vacuum chamber;

[0105] an exhausting unit for exhausting interior of the vacuum chamber;

[0106] a pressure-regulating valve for controlling the interior of thevacuum chamber to a specified pressure;

[0107] a substrate electrode for placing thereon a substrate within thevacuum chamber;

[0108] an antenna provided opposite to the substrate electrode; and

[0109] high-frequency power supply capable of supplying a high-frequencypower having a frequency of 50 MHz to 3 GHz to the antenna,

[0110] the plasma processing apparatus further comprising:

[0111] a dielectric plate sandwiched between the antenna and the vacuumchamber, both the antenna and the dielectric plate projecting into thevacuum chamber;

[0112] an antenna cover for covering both an inner side face of anannular and recessed slit and the antenna with the slit provided betweenthe antenna and the vacuum chamber; and

[0113] a slit cover for covering a bottom face of the slit andsupporting the antenna cover, where the slit cover is fixed to a wallsurface of the vacuum chamber so that the antenna cover is fixed.Therefore, a plasma processing apparatus which is less liable tooccurrence of dust can be provided.

[0114] Also, according to the fourth aspect of the present invention,there is provided a plasma processing apparatus comprising:

[0115] a vacuum chamber;

[0116] a gas supply unit for supplying gas into the vacuum chamber;

[0117] an exhausting unit for exhausting interior of the vacuum chamber;

[0118] a pressure-regulating valve for controlling the interior of thevacuum chamber to a specified pressure;

[0119] a substrate electrode for placing thereon a substrate within thevacuum chamber;

[0120] an antenna provided opposite to the substrate electrode; and

[0121] high-frequency power supply capable of supplying a high-frequencypower having a frequency of 50 MHz to 3 GHz to the antenna,

[0122] the plasma processing apparatus further comprising:

[0123] a dielectric plate sandwiched between the antenna and the vacuumchamber, both the antenna and the dielectric plate projecting into thevacuum chamber;

[0124] an antenna cover for covering both an inner side face of anannular and recessed slit and the antenna with the slit provided betweenthe antenna and the vacuum chamber;

[0125] a heat-conducting sheet provided between the antenna and theantenna cover; and

[0126] a refrigerant feed unit for making a refrigerant flow to theantenna. Therefore, a plasma processing apparatus which is less liableto occurrence of dust and cracks of the antenna cover can be provided.

[0127] Although the present invention has been fully described inconnection with the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. A plasma processing method for generating plasmain a vacuum chamber and processing a substrate placed on a substrateelectrode, the plasma being generated by supplying a high-frequencypower having a frequency of 50 MHz to 3 GHz to an antenna providedopposite to the substrate electrode while interior of the vacuum chamberis controlled to a specified pressure by supplying a gas into the vacuumchamber and exhausting the interior of the vacuum chamber, the methodcomprising: with a dielectric plate being sandwiched between the antennaand the vacuum chamber and both the antenna and the dielectric plateprojecting into the vacuum chamber, controlling plasma distribution onthe substrate with an annular and recessed slit provided between theantenna and the vacuum chamber; and processing the substrate in a statewhere the antenna cover is fixed by making both an inner side face ofthe slit and the antenna covered with an antenna cover, making a bottomface of the slit covered with a slit cover, supporting the antenna coverby the slit cover, and fixing the slit cover to a wall surface of thevacuum chamber.
 2. A plasma processing method according to claim 1,wherein the substrate is processed with the slit cover is a conductorand with electric conduction between the slit cover and thevacuum-chamber wall surface ensured by a spiral tube.
 3. A plasmaprocessing method according to claim 1, wherein the substrate isprocessed with the slit cover is an insulating member.
 4. A plasmaprocessing method for generating plasma in a vacuum chamber andprocessing a substrate placed on a substrate electrode within the vacuumchamber, the plasma being generated by supplying a high-frequency powerhaving a frequency of 50 MHz to 3 GHz to an antenna provided opposite tothe substrate electrode while interior of the vacuum chamber iscontrolled to a specified pressure by supplying a gas into the vacuumchamber and exhausting the interior of the vacuum chamber, the methodcomprising: with a dielectric plate being sandwiched between the antennaand the vacuum chamber and both the antenna and the dielectric plateprojecting into the vacuum chamber, controlling plasma distribution onthe substrate by an annular and recessed slit provided between theantenna and the vacuum chamber; and processing the substrate whilecontrolling temperature of the antenna by making both an inner side faceof the slit and the antenna covered with an antenna cover and applying arefrigerant flow to the antenna while ensuring heat conduction betweenthe antenna and the antenna cover by a heat-conducting sheet providedbetween the antenna and the antenna cover.
 5. A plasma processing methodaccording to claim 4, wherein the substrate is processed while thetemperature of the antenna is controlled with the heat-conducting sheetbeing made from a resin having elasticity and having a dielectric losstangent of more than 0 and not more than 0.01.
 6. A plasma processingmethod according to claim 4, wherein the substrate is processed whilethe temperature of the antenna is controlled with the heat-conductingsheet having a thickness of 0.03 mm to 3 mm.
 7. A plasma processingmethod according to claim 1, wherein the antenna cover is made of 1 mmto 10 mm thick quartz glass.
 8. A plasma processing method according toclaim 1, wherein the substrate is processed with the antenna cover beingmade of 1 mm to 10 mm thick insulative silicon.
 9. A plasma processingmethod according to claim 1, wherein the substrate is processed with thefrequency of the high-frequency power supplied to the antenna beingwithin a range of 50 MHz to 300 MHz.
 10. A plasma processing apparatuscomprising: a vacuum chamber; a gas supply unit for supplying gas intothe vacuum chamber; an exhausting unit for exhausting interior of thevacuum chamber; a pressure-regulating valve for controlling the interiorof the vacuum chamber to a specified pressure; a substrate electrode forplacing thereon a substrate within the vacuum chamber; an antennaprovided opposite to the substrate electrode; and high-frequency powersupply capable of supplying a high-frequency power having a frequency of50 MHz to 3 GHz to the antenna, the plasma processing apparatus furthercomprising: a dielectric plate sandwiched between the antenna and thevacuum chamber, both the antenna and the dielectric plate projectinginto the vacuum chamber; an antenna cover for covering both an innerside face of an annular and recessed slit and the antenna with the slitprovided between the antenna and the vacuum chamber; and a slit coverfor covering a bottom face of the slit and supporting the antenna cover,where the slit cover is fixed to a wall surface of the vacuum chamber sothat the antenna cover is fixed.
 11. A plasma processing apparatusaccording to claim 10, wherein the slit cover is a conductor andelectric conduction between the slit cover and the vacuum-chamber wallsurface is ensured by a spiral tube.
 12. A plasma processing apparatusaccording to claim 10, wherein the slit cover is a dielectric substance.13. A plasma processing apparatus comprising: a vacuum chamber; a gassupply unit for supplying gas into the vacuum chamber; an exhaustingunit for exhausting interior of the vacuum chamber; apressure-regulating valve for controlling the interior of the vacuumchamber to a specified pressure; a substrate electrode for placingthereon a substrate within the vacuum chamber; an antenna providedopposite to the substrate electrode; and high-frequency power supplycapable of supplying a high-frequency power having a frequency of 50 MHzto 3 GHz to the antenna, the plasma processing apparatus furthercomprising: a dielectric plate sandwiched between the antenna and thevacuum chamber, both the antenna and the dielectric plate projectinginto the vacuum chamber; an antenna cover for covering both an innerside face of an annular and recessed slit and the antenna with the slitprovided between the antenna and the vacuum chamber; a heat-conductingsheet provided between the antenna and the antenna cover; and arefrigerant feed unit for making a refrigerant flow to the antenna. 14.A plasma processing apparatus according to claim 13, wherein theheat-conducting sheet is made from a resin having elasticity and havinga dielectric loss tangent of more than 0 and not more than 0.01.
 15. Aplasma processing apparatus according to claim 13, wherein theheat-conducting sheet has a thickness of 0.03 mm to 3 mm.
 16. A plasmaprocessing apparatus according to claim 10, wherein the antenna cover ismade of 1 mm to 10 mm thick quartz glass.
 17. A plasma processingapparatus according to claim 10, wherein the antenna cover is made of 1mm to 10 mm thick insulative silicon.
 18. A plasma processing apparatusaccording to claim 10, wherein the frequency of the high-frequency powersupplied to the antenna is within a range of 50 MHz to 300 MHz.